This proposal is part of a long term plan to study the role of sensory information in motor behavior. The jaw system provides an attractive model for these studies for the following reasons: 1) jaw movements in carnivores are relatively simple and directed towards precisely occluding the teeth, an objective which is expected to require considerable sensory feedback; 2) the sensory receptors surrounding the teeth provide a simple and functionally interpretable response directly related to the magnitude and direction of tooth displacement. The purpose of the experiments in this proposal is to determine how directional and force-specific sensory information from the periodontal ligament is processed at the interneuronal level. Since these receptors also have disynaptic connections to trigeminal motorneurons, the possibility that they are used in controlling the direction and magnitude of bite force will also be investigated by examining the specificity of individual periodontal interneuronal projections. The results of these experiments will lead to a better understanding of the role of tooth mechanoreceptors in jaw movement, and will be potentially useful in the clinical management of occlusal interferences. The results may also be applied to determining the effects of tooth loss on sensory input, as well as identifying the role of periodontal feedback in bruxism.